The "next man up" philosophy will likely face a stern test in the coming weeks

No success comes without a cost, and sometimes that cost can be "significant".

That's the word Mike Tomlin used to broadly describe the Steelers three injuries suffered in the Week 3 thrashing - yes, a thrashing - of the Carolina Panthers.

Ike Taylor, the much-beloved, veteran cornerback and starter, will clearly miss an extended period of time after suffering a gruesome broken arm at the hands of teammate Lawrence Timmons. It's too early to know how long he could miss or, indeed, if it signals the end of his career. But at the very least, he's expected to miss two months.

Rookie linebacker Ryan Shazier injured his right knee, again with involvement from Lawrence Timmons, and was limping significantly as he left the field. Shazier is reported to have sprained his MCL, and we will have to await further news on the situation.

Outside linebacker Jarvis Jones, on the other hand, is out indefinitely after suffering a wrist injury.

It's too early to even guess the extent of Shazier's and Jones' injuries, but both players (and of course Taylor) will miss some time.

Which means that it's time to invoke the age-old Steelers' philosophy of "next man up".

In terms of the Steelers' base defense, the next men up seem pretty straightforward. William Gay will replace Ike Taylor as the starting cornerback and, although the team prefers to play him at nickel, he has demonstrated over the course of the 2013 season that he can be competent when called on.

Ryan Shazier will very likely be replaced by linebacker Sean Spence, who could see his first real opportunity to make an impact in the Steelers defense after recovering from a gruesome knee injury in his rookie season. Spence looked competent in both preseason and the limited action he has seen during the season. With the increased knowledge he has gained of this defense, he may even be a short-term upgrade over the learning-on-his-feet Shazier.

Jarvis Jones' replacement will almost certainly be free-agent acquisition Arthur Moats, who provided some solid rush against the Panthers' beleaguered line, as well a notching a sack in the process.

What sits behind these replacements however, in terms of depth, is an entirely different story.

The Steelers opted to keep only three true outside linebackers on the 53-man roster. Although Lawrence Timmons could play there briefly in a very tight pinch and Terence Garvin has practiced inside and out, a roster move will almost certainly be forthcoming. Howard Jones, a preseason darling of fans, currently resides on the practice squad and could be a prime candidate for a call-up to the adults' table.

At inside linebacker, the Steelers are more set with Terence Garvin and Vince Williams able to step in and spell Spence when required.

In the secondary Antwon Blake and Brice McCain have both been pushed up the depth chart backing up Cortez Allen and William Gay, but things get more interesting when you consider the personnel for the Steelers' sub-packages.

Taylor, Jones and Shazier were all features of the Steelers sub-packages, and their absences could provide an opportunity for some of the younger, less-featured players on the roster to make an impact.

Shamarko Thomas and Robert Golden both made their presence felt on special teams against the Panthers, but they've seen precious few snaps on defense. Thomas and Golden are young, athletic safeties and could have a chance to make an impact in Nickel or Dime packages, although veteran safety Will Allen might have the inside track due to experience.

Likewise, Antwon Blake could see increased action when the team opts to put three cornerbacks on the field, as it did against the Panthers, most noticeably lined up against Carolina's hulking rookie Kelvin Benjamin.

As for the linebackers, Sean Spence has been billed as athletic enough to play in sub-packages and, by all accounts, he should stay on the field in virtually every situation. Terence Garvin, a second-year, undrafted free agent, played in the Steelers' sub-packages in 2013, so that experience should serve him well if he's called on to play the role of an uber-athletic (albeit undersized) linebacker tasked with coverage responsibilities.

In any event, it seems extremely likely that the Steelers will be without Taylor, Shazier and Jones for an extended period of time. Their absence requires the next man behind them to step up. That's how great teams operate, and that's what the Steelers will require as their young defense continues to develop after a bumpy start.

The responsibility falls not only on those pressed into starting duties, but to their back-ups as well, who will be required to spell the starters and, in the worst-case scenario, step in themselves.

One man's misery is another man's opportunity, and opportunity now abounds for those lower on the depth chart to make an impact in both the base and sub-package defenses.

For better or worse, the Steelers will once again look the "next man." That isn't always a bad thing; just ask James Harrison.